The U.S. Department of Energy (DOE), as the steward for U.S. energy policy, has long held the principal responsibility for understanding how energy production may result in climate change and how climate change may impact energy production. During the past four decades, DOE’s Office of Science Biological and Environmental Research (BER) program has sponsored research focused on specific aspects of earth system models to improve the understanding of processes represented in these models.

The Atmospheric System Research (ASR) program is a key U.S. research activity addressing a broad area of uncertainty in earth system models: the interdependence of clouds, atmospheric aerosols, and precipitation and how they influences the radiation balance. ASR coordinates closely with the Atmospheric Radiation Measurement (ARM) user facility and ASR research takes advantage of ARM’s suite of measurements of radiation, aerosols, clouds, precipitation, and thermodynamics from its long-term fixed sites, mobile facility deployments, and aerial facility campaigns.

Within ASR, long-term observational data sets are supplemented with process models, laboratory studies, and shorter-duration ground-based and airborne field campaigns to target specific atmospheric processes at various locations and under diverse atmospheric conditions. Earth system models incorporate ASR research results to both understand the processes that govern atmospheric components and to advance earth system model capabilities with greater certainty. ASR seeks to improve process-level understanding of the life cycles of aerosols, clouds, and precipitation and their representation in dynamic models across a range of scales.

In close collaboration with the ARM user facility, ASR seeks to improve understanding of the key cloud, aerosol, precipitation, and radiation processes that affect the Earth’s radiative balance and hydrological cycle, especially processes that limit the predictive ability of regional and global models.

ASR has four priority research areas corresponding to atmospheric regimes with large uncertainties in earth system prediction—aerosol processes, warm boundary-layer processes, convective processes, and high-latitude processes. To better connect research teams working on the processes and process interactions within each of these areas, ASR is organized into four working groups:

  • Aerosol Processes – understanding of processes governing the spatial and temporal distribution of atmospheric particles and their chemical, microphysical, and optical properties.
  • Warm Boundary Layer Processes – understanding and model representation of processes controlling the structural and radiative properties of clouds, aerosols and their interactions with the underlying surface in the lowest few kilometers of the atmosphere.
  • Convective Processes – understanding and model representation of convective cloud processes and properties including cloud cover, precipitation, life cycle, dynamics, and microphysics over a range of spatial scales.
  • High-Latitude Processes – understanding and model representation of cloud, aerosol, and surface-interaction processes controlling the surface energy budgets in northern and southern high latitude regions.

Becoming ASR

Prior to fiscal year 2009, the principal observation-based DOE programs examining atmospheric processes critical for improving earth system models were the Atmospheric Radiation Measurement (ARM) Program, the Atmospheric Science Program (ASP), and the ARM user facility (ARM). Beginning in 1990, these programs coordinated complementary approaches to quantify the effects of clouds and aerosols on the atmosphere’s radiation balance. The two programs coordinated several joint, field campaigns—typically at ARM facility observatories—thereby combining the distinct measurement scales, methodologies, and expertise available within the two programs to yield complementary data on the same processes, which has led to new insights and understanding.

Studies by the ARM Program focused on clouds and radiative feedbacks based mainly on the long-term observational record from the heavily instrumented ARM facility fixed sites and the first ARM Mobile Facility, supplemented with periodic intensive field campaigns at these sites. In contrast, ASP research made extensive use of controlled laboratory experiments to study key atmospheric processes, especially those involving chemical reactions or composition-dependent aerosol properties, and extended these into the atmospheric environment using in situ measurements in intensive short-term field campaigns.

The October 2009 merger of the ARM Program and ASP into the ASR program brought together ARM expertise in continuous remote sensing measurements of cloud properties and aerosol influences on radiation with the ASP expertise for in situ characterization of aerosol properties, evolution, and cloud interactions.